Early stages of platinum electrodeposition on highly oriented pyrolytic graphite: scanning tunneling microscopy imaging and reaction pathway
The early stages of Pt electrodeposition (0.675-0.620 V vs RHE) on highly oriented pyrolytic graphite (HOPG) from chloroplatinic acid at 25 °C have been studied by ex-situ STM and SEM imaging complemented with electrochemical data. Nucleation and 3D growth of Pt initiate at HOPG surface defects. Lar...
| Autores: | , , , , , , |
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| Formato: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 1993 |
| País: | Argentina |
| Recursos: | Universidad Nacional de La Plata |
| Repositorio: | SEDICI (UNLP) |
| Idioma: | inglés |
| OAI Identifier: | oai:sedici.unlp.edu.ar:10915/80551 |
| Acesso em linha: | http://sedici.unlp.edu.ar/handle/10915/80551 |
| Access Level: | acceso abierto |
| Palavra-chave: | Ciencias Exactas Química scanning tunneling microscopy Platino (Metal) pyrolitic graphite electrodeposition scanning electron microscopy Electroquímica |
| Resumo: | The early stages of Pt electrodeposition (0.675-0.620 V vs RHE) on highly oriented pyrolytic graphite (HOPG) from chloroplatinic acid at 25 °C have been studied by ex-situ STM and SEM imaging complemented with electrochemical data. Nucleation and 3D growth of Pt initiate at HOPG surface defects. Large Pt agglomerates containing flat crystallites with well-defined geometries are found around HOPG steps. Pt crystallites formed by 1-2 nm size clusters become more compact as the electrodeposition potential is shifted negatively or the Pt electrodeposited charge is increased. High-resolution STM imaging reveals large uncovered HOPG areas with the nearest-neighbor C-C distance d = 0.24 ± 0.02 nm and fiat hexagonal Pt crystallites. Electrochemical data combined with STM imaging can be interpreted in terms of a diffusion-controlled Pt(IV) to Pt(II) reaction at HOPG and a surface reaction leading to Pt(0) at HOPG defects. |
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